Film forming method and film forming device

ABSTRACT

A plasma  10  is generated within a film formation chamber  2,  and mainly a nitrogen gas  11  is excited within the film formation chamber  2.  Then, the excited nitrogen gas  11  is mixed with a diborane gas  13  diluted with a hydrogen gas to react them, thereby forming a boron nitride film  15  on a substrate  4.  At the initial stage of film formation, the nitrogen gas  11  is supplied in excess to suppress the occurrence of an amorphous phase on the interface. As a result, the boron nitride film  15  improved in moisture absorption resistance on the interface with the substrate and maintaining low dielectric constant properties is formed.

TECHNICAL FIELD

[0001] This invention relates to a film forming method and a filmforming apparatus for forming a boron nitride film and a boroncarbonitride film.

BACKGROUND ART

[0002] In an integrated circuit, a silicon dioxide film (SiO₂ film) bythe plasma CVD (chemical vapor deposition) method has so far been usedas an interlayer dielectric film. However, because of high integrationof transistors and speeding of a switching action, losses due tocapacitance between wirings have posed problems. To eliminate theselosses, it is necessary to decrease the relative dielectric constant ofthe interlayer dielectric film, so that an interlayer dielectric filmwith a lower relative dielectric constant has been demanded. Under thesecircumstances, films of organic materials (for example, organosiliconfilms or films of amorphous carbon incorporating fluorine) can beprovided with a very low relative dielectric constant (relativedielectric constant κ=2.5 or less), but these films have beenproblematical in mechanical and chemical resistance and thermalconductivity. Adhesion of the films has also presented a problem, andtheir moisture absorption resistance has been a problem in terms ofdensity.

[0003] Under these circumstances, boron nitride (BN) and boroncarbonitride (BNC), which are excellent in heat resistance and have avery low relative dielectric constant (relative dielectric constantκ=2.5 or less), are attracting attention. However, techniques forforming a BN film or a BNC film by the plasma CVD (chemical vapordeposition) method have not been established, and the advent of a filmforming method and a film forming apparatus capable of forming a BN filmand a BNC film as products is in eager demand.

[0004] The present invention has been accomplished in view of the abovesituations, and its object is to provide a film forming method and afilm forming apparatus which can form films of boron nitride and boroncarbonitride.

DISCLOSURE OF THE INVENTION

[0005] The film forming method of the present invention comprisesgenerating a plasma within a film formation chamber, exciting mainly anitrogen gas within the film formation chamber, and then mixing theexcited nitrogen gas with a boron-based gas to react them, therebyforming a boron nitride film on a substrate, the method characterized bysupplying an amorphous phase occurrence suppressing gas at an initialstage of film formation to suppress occurrence of an amorphous phase onan interface.

[0006] Because of this feature, there can be formed a boron nitride filmimproved in moisture absorption resistance on the substrate interfaceand maintaining low dielectric constant properties.

[0007] The film forming method of the present invention comprisesgenerating a plasma within a film formation chamber, exciting mainly anitrogen gas within the film formation chamber, and then mixing theexcited nitrogen gas with a boron-based gas to react them, therebyforming a boron nitride film on a substrate, the method characterized byrendering a flow rate of the nitrogen gas present in excess at aninitial stage of film formation to suppress occurrence of an amorphousphase on an interface.

[0008] Because of this feature, there can be formed a boron nitride filmimproved in moisture absorption resistance on the substrate interfaceand maintaining low dielectric constant properties.

[0009] The film forming method of the present invention comprisesgenerating a plasma within a film formation chamber, exciting mainly anitrogen gas within the film formation chamber, and then mixing theexcited nitrogen gas with a boron-based gas to react them, therebyforming a boron nitride film on a substrate, the method characterized byrendering a flow rate of a hydrogen gas present in excess at an initialstage of film formation to suppress occurrence of an amorphous phase onan interface.

[0010] Because of this feature, there can be formed a boron nitride filmimproved in moisture absorption resistance on the substrate interfaceand maintaining low dielectric constant properties.

[0011] The film forming method of the present invention comprisesgenerating a plasma within a film formation chamber, exciting mainly anitrogen gas within the film formation chamber, and then mixing theexcited nitrogen gas with a boron-based gas and an organic gas orevaporated carbon to react them, thereby forming a boron carbonitridefilm on a substrate, the method characterized by supplying an amorphousphase occurrence suppressing gas at an initial stage of film formationto suppress occurrence of an amorphous phase on an interface.

[0012] Because of this feature, there can be formed a boron carbonitridefilm improved in moisture absorption resistance on the substrateinterface and maintaining low dielectric constant properties.

[0013] The film forming method of the present invention comprisesgenerating a plasma within a film formation chamber, exciting mainly anitrogen gas within the film formation chamber, and then mixing theexcited nitrogen gas with a boron-based gas and an organic gas orevaporated carbon to react them, thereby forming a boron carbonitridefilm on a substrate, the method characterized by rendering a flow rateof the nitrogen gas present in excess at an initial stage of filmformation to suppress occurrence of an amorphous phase on an interface.

[0014] Because of this feature, there can be formed a boron carbonitridefilm improved in moisture absorption resistance on the substrateinterface and maintaining low dielectric constant properties.

[0015] The film forming method of the present invention comprisesgenerating a plasma within a film formation chamber, exciting mainly anitrogen gas within the film formation chamber, and then mixing theexcited nitrogen gas with a boron-based gas and an organic gas orevaporated carbon to react them, thereby forming a boron carbonitridefilm on a substrate, the method characterized by rendering a flow rateof a hydrogen gas present in excess at an initial stage of filmformation to suppress occurrence of an amorphous phase on an interface.

[0016] Because of this feature, there can be formed a boron carbonitridefilm improved in moisture absorption resistance on the substrateinterface and maintaining low dielectric constant properties.

[0017] The film forming method of the present invention comprisesgenerating a plasma within a film formation chamber, exciting mainly anitrogen gas within the film formation chamber, and then mixing theexcited nitrogen gas with a boron-based gas and an organic gas orevaporated carbon to react them, thereby forming a boron carbonitridefilm on a substrate, the method characterized by rendering a flow rateof a hydrocarbon-based gas present in excess at an initial stage of filmformation to suppress occurrence of an amorphous phase on an interface.

[0018] Because of this feature, there can be formed a boron carbonitridefilm improved in moisture absorption resistance on the substrateinterface and maintaining low dielectric constant properties.

[0019] The film forming method of the present invention comprisesgenerating a plasma within a film formation chamber, exciting mainly anitrogen gas within the film formation chamber, and then mixing theexcited nitrogen gas with a boron-based gas to react them, therebyforming a boron nitride film on a substrate, the method characterized byrendering a flow rate of the boron-based gas present in excess at afinal stage of film formation to promote occurrence of an amorphousphase on a surface of the film, and also mixing an amorphous phaseinactivating gas.

[0020] Because of this feature, there can be formed a boron nitride filmincreased in density on the surface of the film and maintaining lowdielectric constant properties, with metal diffusion being suppressedand without impairment of moisture absorption properties.

[0021] The film forming method of the present invention comprisesgenerating a plasma within a film formation chamber, exciting mainly anitrogen gas within the film formation chamber, and then mixing theexcited nitrogen gas with a boron-based gas to react them, therebyforming a boron nitride film on a substrate, the method characterized byrendering a flow rate of the boron-based gas present in excess at afinal stage of film formation to promote occurrence of an amorphousphase on a surface of the film, and also mixing a hydride to inactivatean amorphous phase.

[0022] Because of this feature, there can be formed a boron nitride filmincreased in density on the surface of the film and maintaining lowdielectric constant properties, with metal diffusion being suppressedand without impairment of moisture absorption properties.

[0023] The film forming method of the present invention comprisesgenerating a plasma within a film formation chamber, exciting mainly anitrogen gas within the film formation chamber, and then mixing theexcited nitrogen gas with a boron-based gas and an organic gas orevaporated carbon to react them, thereby forming a boron carbonitridefilm on a substrate, the method characterized by rendering a flow rateof the boron-based gas present in excess at a final stage of filmformation to promote occurrence of an amorphous phase on a surface ofthe film, and also mixing an amorphous phase inactivating gas.

[0024] Because of this feature, there can be formed a boron carbonitridefilm increased in density on the surface of the film and maintaining lowdielectric constant properties, with metal diffusion being suppressedand without impairment of moisture absorption properties.

[0025] The film forming method of the present invention comprisesgenerating a plasma within a film formation chamber, exciting mainly anitrogen gas within the film formation chamber, and then mixing theexcited nitrogen gas with a boron-based gas and an organic gas orevaporated carbon to react them, thereby forming a boron carbonitridefilm on a substrate, the method characterized by rendering a flow rateof the boron-based gas present in excess at a final stage of filmformation to promote occurrence of an amorphous phase on a surface ofthe film, and also mixing a hydride to inactivate the amorphous phase.

[0026] Because of this feature, there can be formed a boron carbonitridefilm increased in density on the surface of the film and maintaining lowdielectric constant properties, with metal diffusion being suppressedand without impairment of moisture absorption properties.

[0027] The film forming method of the present invention comprisesgenerating a plasma within a film formation chamber, exciting mainly anitrogen gas within the film formation chamber, and then mixing theexcited nitrogen gas with a boron-based gas and an organic gas orevaporated carbon to react them, thereby forming a boron carbonitridefilm on a substrate, the method characterized by rendering a flow rateof the boron-based gas present in excess at a final stage of filmformation to promote occurrence of an amorphous phase on a surface ofthe film, and also stopping the plasma and mixing a hydrocarbon materialto inactivate the amorphous phase.

[0028] Because of this feature, there can be formed a boron carbonitridefilm increased in density on the surface of the film and maintaining lowdielectric constant properties, with metal diffusion being suppressedand without impairment of moisture absorption properties.

[0029] The film forming method of the present invention comprisesgenerating a plasma within a film formation chamber, exciting mainly anitrogen gas within the film formation chamber, and then mixing theexcited nitrogen gas with a boron-based gas and an organic gas orevaporated carbon to react them, thereby forming a boron carbonitridefilm on a substrate, the method characterized by rendering a flow rateof the boron-based gas present in excess at a final stage of filmformation to promote occurrence of an amorphous phase on a surface ofthe film, and also stopping the plasma and mixing a hydride and ahydrocarbon material to inactivate the amorphous phase.

[0030] Because of this feature, there can be formed a boron carbonitridefilm increased in density on the surface of the film and maintaining lowdielectric constant properties, with metal diffusion being suppressedand without impairment of moisture absorption properties.

[0031] The film forming method of the present invention comprisesgenerating a plasma within a film formation chamber, exciting mainly anitrogen gas within the film formation chamber, and then mixing theexcited nitrogen gas with a boron-based gas to react them, therebyforming a boron nitride film on a substrate, the method characterized bysupplying an amorphous phase occurrence suppressing gas at an initialstage of film formation to suppress occurrence of an amorphous phase onan interface, rendering a flow rate of the boron-based gas present inexcess at a final stage of film formation to promote occurrence of anamorphous phase on a surface of the film, and also mixing an amorphousphase inactivating gas.

[0032] Because of this feature, there can be formed a boron nitride filmimproved in moisture absorption resistance on the substrate interface,maintaining low dielectric constant properties, increased in density onthe surface of the film and maintaining low dielectric constantproperties, with metal diffusion being suppressed and without impairmentof moisture absorption properties.

[0033] The film forming method of the present invention comprisesgenerating a plasma within a film formation chamber, exciting mainly anitrogen gas within the film formation chamber, and then mixing theexcited nitrogen gas with a boron-based gas and an organic gas orevaporated carbon to react them, thereby forming a boron carbonitridefilm on a substrate, the method characterized by supplying an amorphousphase occurrence suppressing gas at an initial stage of film formationto suppress occurrence of an amorphous phase on an interface, renderinga flow rate of the boron-based gas present in excess at a final stage offilm formation to promote occurrence of an amorphous phase on a surfaceof the film, and also mixing an amorphous phase inactivating gas.

[0034] Because of this feature, there can be formed a boron carbonitridefilm improved in moisture absorption resistance on the substrateinterface, maintaining low dielectric constant properties, increased indensity on the surface of the film and maintaining low dielectricconstant properties, with metal diffusion being suppressed and withoutimpairment of moisture absorption properties.

[0035] The film forming method is characterized in that the boron-basedgas is a diborane gas diluted with a hydrogen gas.

[0036] The film forming apparatus of the present invention has plasmageneration means provided in an upper part of a film formation chamberfor generating a plasma within the film formation chamber, a substrateholding portion provided in a lower part of the film formation chamber,nitrogen gas introduction means for introducing a nitrogen gas into thefilm formation chamber, boron-based gas introduction means forintroducing a boron-based gas to an interior of the film formationchamber below the nitrogen gas introduction means, and suppressing gasintroduction means for introducing an amorphous phase occurrencesuppressing gas at an initial stage of film formation in order tosuppress occurrence of an amorphous phase on an interface.

[0037] Because of this feature, a plasma is generated within a filmformation chamber, mainly a nitrogen gas is excited within the filmformation chamber, and then the excited nitrogen gas is mixed with aboron-based gas to react them, thereby forming a boron nitride film on asubstrate. In this process, an amorphous phase occurrence suppressinggas is supplied at an initial stage of film formation, wherebyoccurrence of an amorphous phase on an interface can be suppressed. As aresult, there can be formed a boron nitride film improved in moistureabsorption resistance on the substrate interface and maintaining lowdielectric constant properties.

[0038] The film forming apparatus of the present invention has plasmageneration means provided in an upper part of a film formation chamberfor generating a plasma within the film formation chamber, a substrateholding portion provided in a lower part of the film formation chamber,nitrogen gas introduction means for introducing a nitrogen gas into thefilm formation chamber, boron-based gas introduction means forintroducing a boron-based gas to an interior of the film formationchamber below the nitrogen gas introduction means, and suppressing gasintroduction means for introducing a nitrogen gas at an initial stage offilm formation in order to render a flow rate of the nitrogen gaspresent in excess within the film formation chamber and suppressoccurrence of an amorphous phase on an interface.

[0039] Because of this feature, a plasma is generated within a filmformation chamber, mainly a nitrogen gas is excited within the filmformation chamber, and then the excited nitrogen gas is mixed with aboron-based gas to react them, thereby forming a boron nitride film on asubstrate. In this process, the flow rate of the nitrogen gas isrendered present in excess at the initial stage of film formation,whereby occurrence of an amorphous phase on an interface can besuppressed. As a result, there can be formed a boron nitride filmimproved in moisture absorption resistance on the substrate interfaceand maintaining low dielectric constant properties.

[0040] The film forming apparatus of the present invention has plasmageneration means provided in an upper part of a film formation chamberfor generating a plasma within the film formation chamber, a substrateholding portion provided in a lower part of the film formation chamber,nitrogen gas introduction means for introducing a nitrogen gas into thefilm formation chamber, boron-based gas introduction means forintroducing a boron-based gas to an interior of the film formationchamber below the nitrogen gas introduction means, and suppressing gasintroduction means for introducing a hydrogen gas at an initial stage offilm formation in order to render a flow rate of the nitrogen gaspresent in excess within the film formation chamber and suppressoccurrence of an amorphous phase on an interface.

[0041] Because of this feature, a plasma is generated within a filmformation chamber, mainly a nitrogen gas is excited within the filmformation chamber, and then the excited nitrogen gas is mixed with aboron-based gas to react them, thereby forming a boron nitride film on asubstrate. In this process, the flow rate of a hydrogen gas is renderedpresent in excess at the initial stage of film formation, wherebyoccurrence of an amorphous phase on an interface can be suppressed. As aresult, there can be formed a boron nitride film improved in moistureabsorption resistance on the substrate interface and maintaining lowdielectric constant properties.

[0042] The film forming apparatus of the present invention has plasmageneration means provided in an upper part of a film formation chamberfor generating a plasma within the film formation chamber, a substrateholding portion provided in a lower part of the film formation chamber,nitrogen gas introduction means for introducing a nitrogen gas into thefilm formation chamber, boron-based gas introduction means forintroducing a boron-based gas and an organic gas or evaporated carbon toan interior of the film formation chamber below the nitrogen gasintroduction means, and suppressing gas introduction means forintroducing an amorphous phase occurrence suppressing gas at an initialstage of film formation in order to suppress occurrence of an amorphousphase on an interface.

[0043] Because of this feature, a plasma is generated within a filmformation chamber, mainly a nitrogen gas is excited within the filmformation chamber, and then the excited nitrogen gas is mixed with aboron-based gas and an organic gas or evaporated carbon to react them,thereby forming a boron carbonitride film on a substrate. In thisprocess, an amorphous phase occurrence suppressing gas is supplied atthe initial stage of film formation, whereby occurrence of an amorphousphase on an interface can be suppressed. As a result, there can beformed a boron carbonitride film improved in moisture absorptionresistance on the substrate interface and maintaining low dielectricconstant properties.

[0044] The film forming apparatus of the present invention has plasmageneration means provided in an upper part of a film formation chamberfor generating a plasma within the film formation chamber, a substrateholding portion provided in a lower part of the film formation chamber,nitrogen gas introduction means for introducing a nitrogen gas into thefilm formation chamber, boron-based gas introduction means forintroducing a boron-based gas and an organic gas or evaporated carbon toan interior of the film formation chamber below the nitrogen gasintroduction means, and suppressing gas introduction means forintroducing a nitrogen gas at an initial stage of film formation inorder to render a flow rate of the nitrogen gas present in excess withinthe film formation chamber and suppress occurrence of an amorphous phaseon an interface.

[0045] Because of this feature, a plasma is generated within a filmformation chamber, mainly a nitrogen gas is excited within the filmformation chamber, and then the excited nitrogen gas is mixed with aboron-based gas and an organic gas or evaporated carbon to react them,thereby forming a boron carbonitride film on a substrate. In thisprocess, the flow rate of the nitrogen gas is rendered present in excessat the initial stage of film formation, whereby occurrence of anamorphous phase on an interface can be suppressed. As a result, therecan be formed a boron carbonitride film improved in moisture absorptionresistance on the substrate interface and maintaining low dielectricconstant properties.

[0046] The film forming apparatus of the present invention has plasmageneration means provided in an upper part of a film formation chamberfor generating a plasma within the film formation chamber, a substrateholding portion provided in a lower part of the film formation chamber,nitrogen gas introduction means for introducing a nitrogen gas into thefilm formation chamber, boron-based gas introduction means forintroducing a boron-based gas and an organic gas or evaporated carbon toan interior of the film formation chamber below the nitrogen gasintroduction means, and suppressing gas introduction means forintroducing a hydrogen gas at an initial stage of film formation inorder to render a flow rate of the hydrogen gas present in excess withinthe film formation chamber and suppress occurrence of an amorphous phaseon an interface.

[0047] Because of this feature, a plasma is generated within a filmformation chamber, mainly a nitrogen gas is excited within the filmformation chamber, and then the excited nitrogen gas is mixed with aboron-based gas and an organic gas or evaporated carbon to react them,thereby forming a boron carbonitride film on a substrate. In thisprocess, the flow rate of a hydrogen gas is rendered present in excessat the initial stage of film formation, thereby suppressing occurrenceof an amorphous phase on an interface. Thus, there can be formed a boroncarbonitride film improved in moisture absorption resistance on thesubstrate interface and maintaining low dielectric constant properties.

[0048] The film forming apparatus of the present invention has plasmageneration means provided in an upper part of a film formation chamberfor generating a plasma within the film formation chamber, a substrateholding portion provided in a lower part of the film formation chamber,nitrogen gas introduction means for introducing a nitrogen gas into thefilm formation chamber, boron-based gas introduction means forintroducing a boron-based gas and an organic gas or evaporated carbon toan interior of the film formation chamber below the nitrogen gasintroduction means, and suppressing gas introduction means forintroducing a hydrocarbon-based gas at an initial stage of filmformation in order to render a flow rate of the hydrocarbon-based gaspresent in excess within the film formation chamber and suppressoccurrence of an amorphous phase on an interface.

[0049] Because of this feature, a plasma is generated within a filmformation chamber, mainly a nitrogen gas is excited within the filmformation chamber, and then the excited nitrogen gas is mixed with aboron-based gas and an organic gas or evaporated carbon to react them,thereby forming a boron carbonitride film on a substrate. In thisprocess, the flow rate of a hydrocarbon-based gas is rendered present inexcess at the initial stage of film formation, whereby occurrence of anamorphous phase on an interface can be suppressed. Thus, there can beformed a boron carbonitride film improved in moisture absorptionresistance on the substrate interface and maintaining low dielectricconstant properties.

[0050] The film forming apparatus of the present invention has plasmageneration means provided in an upper part of a film formation chamberfor generating a plasma within the film formation chamber, a substrateholding portion provided in a lower part of the film formation chamber,nitrogen gas introduction means for introducing a nitrogen gas into thefilm formation chamber, boron-based gas introduction means forintroducing a boron-based gas to an interior of the film formationchamber below the nitrogen gas introduction means, promoting gasintroduction means for rendering a flow rate of the boron-based gaspresent in excess at a final stage of film formation to promoteoccurrence of an amorphous phase on a surface of a film, andinactivating gas introduction means for mixing an amorphous phaseinactivating gas at the final stage of film formation.

[0051] Because of this feature, a plasma is generated within a filmformation chamber, a nitrogen gas is mainly excited within the filmformation chamber, and then the excited nitrogen gas is mixed with aboron-based gas to react them, thereby forming a boron nitride film on asubstrate. In this process, the flow rate of the boron-based gas isrendered present in excess at the final stage of film formation, wherebyoccurrence of an amorphous phase on the surface of the film can bepromoted, and moreover an amorphous phase inactivating gas can be mixed.As a result, there can be formed a boron nitride film increased indensity on the surface of the film and maintaining low dielectricconstant properties, with metal diffusion being suppressed and withoutimpairment of moisture absorption properties.

[0052] The film forming apparatus of the present invention has plasmageneration means provided in an upper part of a film formation chamberfor generating a plasma within the film formation chamber, a substrateholding portion provided in a lower part of the film formation chamber,nitrogen gas introduction means for introducing a nitrogen gas into thefilm formation chamber, boron-based gas introduction means forintroducing a boron-based gas to an interior of the film formationchamber below the nitrogen gas introduction means, promoting gasintroduction means for rendering a flow rate of the boron-based gaspresent in excess at a final stage of film formation to promoteoccurrence of an amorphous phase on a surface of a film, andinactivating gas introduction means for mixing a hydrogen gas at thefinal stage of film formation in order to inactivate the amorphousphase.

[0053] Because of this feature, a plasma is generated within a filmformation chamber, mainly a nitrogen gas is excited within the filmformation chamber, and then the excited nitrogen gas is mixed with aboron-based gas to react them, thereby forming a boron nitride film on asubstrate. In this process, the flow rate of the boron-based gas isrendered present in excess at the final stage of film formation, wherebyoccurrence of an amorphous phase on the surface of the film can bepromoted, and moreover a hydride can be mixed to inactivate theamorphous phase. As a result, there can be formed a boron nitride filmincreased in density on the surface of the film and maintaining lowdielectric constant properties, with metal diffusion being suppressedand without impairment of moisture absorption properties.

[0054] The film forming apparatus of the present invention has plasmageneration means provided in an upper part of a film formation chamberfor generating a plasma within the film formation chamber, a substrateholding portion provided in a lower part of the film formation chamber,nitrogen gas introduction means for introducing a nitrogen gas into thefilm formation chamber, boron-based gas introduction means forintroducing a boron-based gas and an organic gas or evaporated carbon toan interior of the film formation chamber below the nitrogen gasintroduction means, promoting gas introduction means for rendering aflow rate of the boron-based gas present in excess at a final stage offilm formation to promote occurrence of an amorphous phase on a surfaceof a film, and inactivating gas introduction means for mixing anamorphous phase inactivating gas at the final stage of film formation.

[0055] Because of this feature, a plasma is generated within a filmformation chamber, mainly a nitrogen gas is excited within the filmformation chamber, and then the excited nitrogen gas is mixed with aboron-based gas and an organic gas or evaporated carbon to react them,thereby forming a boron carbonitride film on a substrate. In thisprocess, the flow rate of the boron-based gas is rendered present inexcess at the final stage of film formation, whereby occurrence of anamorphous phase on the surface of the film can be promoted, and moreoveran amorphous phase inactivating gas can be mixed. As a result, there canbe formed a boron carbonitride film increased in density on the surfaceof the film and maintaining low dielectric constant properties, withmetal diffusion being suppressed and without impairment of moistureabsorption properties.

[0056] The film forming apparatus of the present invention has plasmageneration means provided in an upper part of a film formation chamberfor generating a plasma within the film formation chamber, a substrateholding portion provided in a lower part of the film formation chamber,nitrogen gas introduction means for introducing a nitrogen gas into thefilm formation chamber, boron-based gas introduction means forintroducing a boron-based gas and an organic gas or evaporated carbon toan interior of the film formation chamber below the nitrogen gasintroduction means, promoting gas introduction means for rendering aflow rate of the boron-based gas present in excess at a final stage offilm formation to promote occurrence of an amorphous phase on a surfaceof a film, and inactivating gas introduction means for mixing a nitrideat the final stage of film formation in order to inactivate theamorphous phase.

[0057] Because of this feature, a plasma is generated within a filmformation chamber, mainly a nitrogen gas is excited within the filmformation chamber, and then the excited nitrogen gas is mixed with aboron-based gas and an organic gas or evaporated carbon to react them,thereby forming a boron carbonitride film on a substrate. In thisprocess, the flow rate of the boron-based gas is rendered present inexcess at the final stage of film formation, whereby occurrence of anamorphous phase on the surface of the film can be promoted, and moreovera hydride is mixed, whereby the amorphous phase can be inactivated. As aresult, there can be formed a boron carbonitride film increased indensity on the surface of the film and maintaining low dielectricconstant properties, with metal diffusion being suppressed and withoutimpairment of moisture absorption properties.

[0058] The film forming apparatus of the present invention has plasmageneration means provided in an upper part of a film formation chamberfor generating a plasma within the film formation chamber, a substrateholding portion provided in a lower part of the film formation chamber,nitrogen gas introduction means for introducing a nitrogen gas into thefilm formation chamber, boron-based gas introduction means forintroducing a boron-based gas and an organic gas or evaporated carbon toan interior of the film formation chamber below the nitrogen gasintroduction means, promoting gas introduction means for rendering aflow rate of the boron-based gas present in excess at a final stage offilm formation to promote occurrence of an amorphous phase on a surfaceof a film, and inactivating gas introduction means for mixing ahydrocarbon material at the final stage of film formation in order toinactivate the amorphous phase.

[0059] Because of this feature, a plasma is generated within a filmformation chamber, mainly a nitrogen gas is excited within the filmformation chamber, and then the excited nitrogen gas is mixed with aboron-based gas and an organic gas or evaporated carbon to react them,thereby forming a boron carbonitride film on a substrate. In thisprocess, the flow rate of the boron-based gas is rendered present inexcess at the final stage of film formation, whereby occurrence of anamorphous phase on the surface of the film can be promoted, and moreoverthe plasma is stopped, and a hydrocarbon material is mixed, whereby theamorphous phase can be inactivated. As a result, there can be formed aboron carbonitride film increased in density on the surface of the filmand maintaining low dielectric constant properties, with metal diffusionbeing suppressed and without impairment of moisture absorptionproperties.

[0060] The film forming apparatus of the present invention has plasmageneration means provided in an upper part of a film formation chamberfor generating a plasma within the film formation chamber, a substrateholding portion provided in a lower part of the film formation chamber,nitrogen gas introduction means for introducing a nitrogen gas into thefilm formation chamber, boron-based gas introduction means forintroducing a boron-based gas and an organic gas or evaporated carbon toan interior of the film formation chamber below the nitrogen gasintroduction means, promoting gas introduction means for rendering aflow rate of the boron-based gas present in excess at a final stage offilm formation to promote occurrence of an amorphous phase on a surfaceof a film, and inactivating gas introduction means for mixing a hydrideand a hydrocarbon material at the final stage of film formation in orderto inactivate the amorphous phase.

[0061] Because of this feature, a plasma is generated within a filmformation chamber, mainly a nitrogen gas is excited within the filmformation chamber, and then the excited nitrogen gas is mixed with aboron-based gas and an organic gas or evaporated carbon to react them,thereby forming a boron carbonitride film on a substrate. In thisprocess, the flow rate of the boron-based gas is rendered present inexcess at the final stage of film formation, whereby occurrence of anamorphous phase on the surface of the film can be promoted, and moreoverthe plasma is stopped, and a hydride and a hydrocarbon material aremixed, whereby the amorphous phase can be inactivated. As a result,there can be formed a boron carbonitride film increased in density onthe surface of the film and maintaining low dielectric constantproperties, with metal diffusion being suppressed and without impairmentof moisture absorption properties.

[0062] The film forming apparatus of the present invention has plasmageneration means provided in an upper part of a film formation chamberfor generating a plasma within the film formation chamber, a substrateholding portion provided in a lower part of the film formation chamber,nitrogen gas introduction means for introducing a nitrogen gas into thefilm formation chamber, boron-based gas introduction means forintroducing a boron-based gas to an interior of the film formationchamber below the nitrogen gas introduction means, suppressing gasintroduction means for introducing an amorphous phase occurrencesuppressing gas at an initial stage of film formation in order tosuppress occurrence of an amorphous phase on an interface, promoting gasintroduction means for rendering a flow rate of the boron-based gaspresent in excess at a final stage of film formation to promoteoccurrence of an amorphous phase on a surface of a film, andinactivating gas introduction means for mixing an amorphous phaseinactivating gas at the final stage of film formation.

[0063] Because of this feature, a plasma is generated within a filmformation chamber, mainly a nitrogen gas is excited within the filmformation chamber, and then the excited nitrogen gas is mixed with aboron-based gas to react them, thereby forming a boron nitride film on asubstrate. In this process, an amorphous phase occurrence suppressinggas is supplied at the initial stage of film formation, wherebyoccurrence of an amorphous phase on an interface can be suppressed.Also, the flow rate of the boron-based gas is rendered present in excessat the final stage of film formation, thereby promoting occurrence of anamorphous phase on the surface of the film, and moreover an amorphousphase inactivating gas can be mixed. As a result, there can be formed aboron nitride film improved in moisture absorption resistance on thesubstrate interface and maintaining low dielectric constant properties,and also increased in density on the surface of the film and maintaininglow dielectric constant properties, with metal diffusion beingsuppressed and without impairment of moisture absorption properties.

[0064] The film forming apparatus of the present invention has plasmageneration means provided in an upper part of a film formation chamberfor generating a plasma within the film formation chamber, a substrateholding portion provided in a lower part of the film formation chamber,nitrogen gas introduction means for introducing a nitrogen gas into thefilm formation chamber, boron-based gas introduction means forintroducing a boron-based gas and an organic gas or evaporated carbon toan interior of the film formation chamber below the nitrogen gasintroduction means, suppressing gas introduction means for introducingan amorphous phase occurrence suppressing gas at an initial stage offilm formation in order to suppress occurrence of an amorphous phase onan interface, promoting gas introduction means for rendering a flow rateof the boron-based gas present in excess at a final stage of filmformation to promote occurrence of an amorphous phase on a surface of afilm, and inactivating gas introduction means for mixing an amorphousphase inactivating gas at the final stage of film formation.

[0065] Because of this feature, a plasma is generated within a filmformation chamber, mainly a nitrogen gas is excited within the filmformation chamber, and then the excited nitrogen gas is mixed with aboron-based gas and an organic gas or evaporated carbon to react them,thereby forming a boron carbonitride film on a substrate. In thisprocess, an amorphous phase occurrence suppressing gas is supplied atthe initial stage of film formation, whereby occurrence of an amorphousphase on an interface can be suppressed. Also, the flow rate of theboron-based gas is rendered present in excess at the final stage of filmformation, thereby promoting occurrence of an amorphous phase on thesurface of the film, and moreover an amorphous phase inactivating gascan be mixed. As a result, there can be formed a boron carbonitride filmimproved in moisture absorption resistance on the substrate interfaceand maintaining low dielectric constant properties, and also increasedin density on the surface of the film and maintaining low dielectricconstant properties, with metal diffusion being suppressed and withoutimpairment of moisture absorption properties.

BRIEF DESCRIPTION OF THE DRAWINGS

[0066]FIG. 1 is a schematic side view of a plasma CVD apparatus as afilm forming apparatus for performing a film forming method according toa first embodiment of the present invention.

[0067]FIG. 2 is a schematic view of the state of firm formationperformed by the present embodiment.

[0068]FIG. 3 is a schematic view of an interface portion.

[0069]FIG. 4 is a schematic view of the state of copper wired on asurface portion.

[0070]FIG. 5 is a schematic side view of a plasma CVD apparatus as afilm forming apparatus for performing a film forming method according toa second embodiment of the present invention.

[0071]FIG. 6 is a schematic view of an interface portion of a filmformed by the present embodiment.

[0072]FIG. 7 is a schematic side view of a plasma CVD apparatus as afilm forming apparatus for performing a film forming method according toa third embodiment of the present invention.

[0073]FIG. 8 is a schematic side view of a plasma CVD apparatus as afilm forming apparatus for performing a film forming method according toa fourth embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

[0074] In preparing boron nitride (BN) with a low dielectric constant,as an interlayer dielectric film of a highly integrated circuit, by theplasma vapor phase process, diborane (B₂H₆) or the like, which isdiluted with a hydrogen (H₂) gas as a diluent gas, has been used as aboron source, and a nitrogen (N₂) gas or the like has been used as anitrogen source. In preparing a boron carbonitride (BNC) film, on theother hand, tetraethoxysilane (Si(O—C₂H₅)₄; hereinafter referred to asTEOS) as an organic gas, evaporated carbon, or the like has further beenused as a carbon source. A plasma has been generated in a reactor, andthese gases have been mixed there to form the film on a predeterminedsubstrate.

[0075] As a problem with formation of the BN film or the BNC film, thereis a concern about aggravation of a low dielectric constant due tomoisture absorption caused by the presence of an amorphous phase at theinterface between the substrate and the film. Moreover, gas escape insubsequent processes is feared. Furthermore, when copper (Cu) is wired,a low density of the surface of the film causes concern about interlayerdielectric breakdown or the like ascribed to diffusion of Cu.

[0076] Hence, the present invention has achieved a film forming methodand a film forming apparatus which can form a BN film or a BNC filmwhile suppressing an amorphous phase at the interface between asubstrate and the film, without aggravating a low dielectric constant.Besides, the present invention has achieved a film forming method and afilm forming apparatus capable of forming a BN film or a BNC film whichdissolves the lowness of density of the film surface in consideration ofmoisture absorption resistance, to attain freedom from diffusion of awired metal (especially Cu), thereby causing no interlayer dielectricbreakdown.

[0077] To describe the present invention in more detail, the inventionwill be illustrated in accordance with the accompanying drawings.

[0078] The film forming method and the film forming apparatus of thepresent invention will be described based on FIGS. 1 to 8.

[0079] The first embodiment is explained based on FIGS. 1 to 4. FIG. 1schematically shows a side view of a plasma CVD apparatus as a filmforming apparatus for performing the film forming method according tothe first embodiment of the present invention. FIG. 2 schematicallyshows the state of firm formation in the present embodiment. FIG. 3schematically shows an interface portion. FIG. 4 schematically shows thestate of copper wired on a surface portion.

[0080] As shown in FIG. 1, a film formation chamber 2 is formed within acylindrical container 1, and a circular ceiling board 3 is provided inan upper part of the container 1. An electrostatic chuck 4, as asubstrate holding portion, is provided in the film formation chamber 2at the center of the container 1. A direct current power source 5 forthe electrostatic chuck is connected to the electrostatic chuck 4 sothat a substrate 6 of a semiconductor (for example, a silicon wafer witha diameter of 300 mm or more) is electrostatically attracted thereto andheld thereon.

[0081] A high frequency antenna 7 of a circular ring shape, for example,is disposed on the ceiling board 3, and a high frequency power source 9is connected to the high frequency antenna 7 via a matching instrument8. By supplying an electric power to the high frequency antenna 7,electromagnetic waves are shot into the film formation chamber 2 of thecontainer 1. The electromagnetic waves shot into the container 1 ionizea gas within the film formation chamber 2 to generate a plasma 10(plasma generation means).

[0082] The container 1 is provided with a nitrogen gas nozzle 12, asnitrogen gas introduction means, for introducing a nitrogen gas (N₂gas)11 (>99.999%) into the film formation chamber 2. A diborane gas nozzle14, as boron-based gas introduction means, is provided for introducing adiborane(B₂H₆)-containing gas 13, as a boron-based gas, to the interiorof the film formation chamber 2 below the nitrogen gas nozzle 12. TheB₂H₆-containing gas 13 introduced into the film formation chamber 2through the diborane gas nozzle 14 is a B₂H₆ gas (1% to 5%) diluted witha hydrogen (H₂) gas.

[0083] With the above-described plasma CVD apparatus, the substrate 6 isplaced on the electrostatic chuck 4 and electrostatically attractedthereto. The N₂ gas 11 is introduced at a predetermined flow ratethrough the nitrogen gas nozzle 12, while the B₂H₆-containing gas 13 isintroduced at a predetermined flow rate through the diborane gas nozzle14. An electric power is supplied from the high frequency power source 9to the high frequency antenna 7 to apply high frequency waves (1 MHz to100 MHz, 1 kW to 10 kW) via the matching instrument 8. As a result,mainly the N₂ gas 11 is excited within the film formation chamber 2 tochange into a plasma state. After the N₂ gas 11 is excited, it is mixedwith the B₂H₆-containing gas 13 and reacted thereby, whereby a boroncarbonitride (BN) film 15 is formed on the substrate 6, as shown in FIG.2. At this time, the temperature of the substrate 6 is set at 200° C. to400° C.

[0084] At the initial stage of film formation, the flow rate of the N₂gas 11 through the nitrogen gas nozzle 12 is rendered present in excessto suppress agglomeration of boron (B), thereby promotingcrystallization of BN and eliminating crystal imperfection. Throughthese means, the occurrence of an amorphous phase at the interface 15 abetween the substrate 6 and the BN film 15 is suppressed. That is, asshown in FIG. 3, the amount of N₂ is made large at the initial stage offilm formation, whereby B is decreased and BN binding is promoted tofacilitate crystallization. In other words, according to the presentembodiment, the nitrogen gas nozzle 12 serves as suppressing gasintroduction means, and the N₂ gas 11 serves as an amorphous phasesuppressing gas. As the suppressing gas introduction means, a nozzle forseparately introducing the N₂ gas 11 can also be provided.

[0085] Since an amorphous phase is known to be the origin of moistureabsorption, suppression of the occurrence of the amorphous phase at theinterface 15 a is very effective for decreasing moisture absorption.After initial-stage film formation, film formation is continued, withthe flow rate ratio being returned to the usual ratio. By so doing,there is obtained the BN film 15 of the desired thickness andmaintaining low dielectric constant properties. The initial-stage filmformation is preferably for a period until a thickness, for example, ofthe order of 100 Å is obtained.

[0086] At the final stage of film formation, the flow rate of B₂H₆through the diborane gas nozzle 14 is rendered present in excess, and anH₂ gas 13 a is newly mixed into the diborane gas nozzle 14, to enhanceimperfection due to B in BN, thereby promoting the occurrence of anamorphous phase at the most superficial surface 15 b of the BN film 15,and also inactivating the amorphous phase. That is, the occurrence ofthe amorphous phase is promoted to attain a close-packed state (toincrease density), and H converted to atoms by the plasma is bound tounbound seeds to inactivate the amorphous phase, thereby increasingmoisture absorption resistance.

[0087] That is, according to the present embodiment, the diborane gasnozzle 14 serves as promoting gas introduction means, the line for newlymixing the H₂ gas 13 a and the diborane gas nozzle 14 serve asinactivating gas introduction means, and the H₂ gas 13 a serves as anamorphous phase inactivating gas. A nozzle for separately introducingthe H₂ gas 13 a may be provided to constitute the inactivating gasintroduction means.

[0088] The most superficial surface 15 b of the BN film 15 is normallyin a rough state. Thus, if other metal (for example, copper: Cu) iswired in this condition, as shown in FIG. 4, diffusion of Cu occurs.According to the present embodiment, the flow rate of B₂H₆ is made anexcess value at the final stage of film formation, thereby promoting theoccurrence of an amorphous phase and increasing density. In addition, anamorphous phase is known to be the origin of moisture absorption, asstated earlier. Thus, the H₂ gas 13 a is mixed to bind H to the unboundseeds, thereby inactivating the amorphous phase, namely, increasingmoisture absorption resistance. Hence, diffusion of Cu is suppressedwithout impairment of moisture absorption resistance.

[0089] As described above, the BN film 15 is produced which has theinterface 15 a where the occurrence of an amorphous phase has beensuppressed, and the most superficial surface 15 b where the occurrenceof an amorphous phase has been promoted to increase density, and wherethe amorphous phase has been inactivated. By so doing, moistureabsorption resistance at the interface with the substrate can beimproved. Furthermore, diffusion of Cu can be suppressed withoutimpairment of moisture absorption properties.

[0090] The second embodiment will be described based on FIGS. 5 and 6.FIG. 5 is a schematic side view of a plasma CVD apparatus as a filmforming apparatus for performing the film forming method according tothe second embodiment of the present invention. FIG. 6 is a schematicview of an interface portion of a film formed by the present embodiment.The same constituent members as the members shown in FIGS. 1 to 4 areassigned the same numerals, and duplicate explanations are omitted.

[0091] In the present embodiment, at the initial stage of filmformation, an H₂ gas 13 b is newly incorporated further into thediborane gas nozzle 14 to render the flow rate of the H₂ present inexcess and remove agglomeration of boron (B), thereby promotingcrystallization of BN and eliminating crystal imperfection. Throughthese means, the occurrence of an amorphous phase at the interface 15 abetween the substrate 6 and the BN film 15 is suppressed. That is, asshown in FIG. 6, the amount of H₂ is made large at the initial stage offilm formation, whereby atomic H in the plasma etches agglomerated B andvaporizes it as BH to leave only BN behind.

[0092] In other words, according to the present embodiment, the line forthe further new H₂ gas 13 b and the diborane gas nozzle 14 serve assuppressing gas introduction means, and the further new H₂ gas 13 bserves as an amorphous phase suppressing gas. As the suppressinggasintroduction means, a nozzle for separately introducing the further newH₂ gas 13 b can also be provided.

[0093] Since an amorphous phase is known to be the origin of moistureabsorption, suppression of the occurrence of the amorphous phase at theinterface 15 a is very effective for decreasing moisture absorption.After initial-stage film formation, film formation is continued, withthe flow rate ratio being returned to the usual ratio. By so doing,there is obtained the BN film 15 of the desired thickness andmaintaining low dielectric constant properties. The initial-stage filmformation is preferably for a period until a thickness, for example, ofthe order of 100 Å is obtained.

[0094] In the present embodiment, the same treatment as in the firstembodiment is performed at the final stage of film formation to form theBN film 15, as stated earlier, which has the interface 15 a where theoccurrence of an amorphous phase has been suppressed, and the mostsuperficial surface 15 b where the occurrence of an amorphous phase hasbeen promoted to increase density, and where the amorphous phase hasbeen inactivated. By so doing, moisture absorption resistance at theinterface with the substrate can be improved. Furthermore, diffusion ofCu can be suppressed without impairment of moisture absorptionproperties.

[0095] The third embodiment will be described based on FIG. 7. FIG. 7 isa schematic side view of a plasma CVD apparatus as a film formingapparatus for performing the film forming method according to the thirdembodiment of the present invention. The same constituent members as themembers shown in FIGS. 1 to 4 are assigned the same numerals, andduplicate explanations are omitted.

[0096] The container 1 is provided with a nitrogen gas nozzle 12 forintroducing a nitrogen gas (N₂ gas) 11 (>99.999%) into the filmformation chamber 2. A mixed gas nozzle 17, as boron-based gasintroduction means, is provided for introducing adiborane(B₂H₆)-containing gas, as a boron-based gas, and atetraethoxysilane (Si(O—C₂H₅)₄; hereinafter referred to as TEOS) gas, asan organic gas, i.e., (B₂H₆-containing gas+TEOS gas) 16, to the interiorof the film formation chamber 2 below the nitrogen gas nozzle 12. TheB₂H₆-containing gas introduced into the film formation chamber 2 throughthe mixed gas nozzle 17 is a B₂H₆ gas (1% to 5%) diluted with a hydrogen(H₂) gas.

[0097] Ethanol or acetone can be employed as the organic gas.

[0098] A hydrocarbon-based gas nozzle 42, as suppressing gasintroduction means, is provided for introducing a hydrocarbon-based gas(for example, methane: CH₄) 41, as an amorphous phase occurrencesuppressing gas, into the interior of the film formation chamber 2 belowthe mixed gas nozzle 17. CH₄ 41 is introduced through thehydrocarbon-based gas nozzle 42 at the initial stage of film formation.As the amorphous phase occurrence suppressing gas, it is possible toapply the N₂ gas 11 shown in the first embodiment, or the H₂ gas 13 bshown in the second embodiment.

[0099] With the above-described plasma CVD apparatus, the N₂ gas 11 isintroduced at a predetermined flow rate through the nitrogen gas nozzle12, while the (B₂H₆-containing gas +TEOS gas) 16 is introduced at apredetermined flow rate through the mixed gas nozzle 17. An electricpower is supplied from the high frequency power source 9 to the highfrequency antenna 7 to apply high frequency waves (1 MHz to 100 MHz, 1kW to 10 kW) via the matching instrument 8. As a result, mainly the N₂gas 11 is excited within the film formation chamber 2 to change into aplasma state. After the N₂ gas 11 is excited, it is mixed with the(B₂H₆-containing gas+TEOS gas) 16 and reacted thereby, whereby a boroncarbonitride (BNC) film 18 is formed on the substrate 6. At this time,the temperature of the substrate 6 is set at 200° C. to 400° C.

[0100] At the initial stage of film formation, the CH₄ 41 is introducedthrough the hydrocarbon-based gas nozzle 42 to suppress agglomeration ofboron (B), thereby promoting crystallization of BNC and eliminatingcrystal imperfection. Through these means, the occurrence of anamorphous phase at the interface between the substrate 6 and the BNCfilm 18 is suppressed. That is, CH₄ 41 is introduced at the initialstage of film formation, whereby CH₄ is converted into CH₃+atomic H inthe plasma. The atomic H etches agglomerated B and vaporizes it as BH.Carbon binds to BN, promoting crystallization of BNC.

[0101] Since an amorphous phase is known to be the origin of moistureabsorption, suppression of the occurrence of the amorphous phase at theinterface is very effective for decreasing moisture absorption. Afterinitial-stage film formation, film formation is continued, with the flowrate ratio being returned to the usual ratio. By so doing, there isobtained the BNC film 18 of the desired thickness and maintaining lowdielectric constant properties. The initial-stage film formation ispreferably for a period until a thickness, for example, of the order of100 Å is obtained.

[0102] At the final stage of film formation, the flow rate of B₂H₆through the mixed gas nozzle 17 is rendered present in excess, and an H₂gas 13 a is newly mixed into the mixed gas nozzle 17, to enhanceimperfection due to B in BNC, thereby promoting the occurrence of anamorphous phase at the most superficial surface of the BNC film 18, andalso inactivating the amorphous phase. That is, the occurrence of theamorphous phase is promoted to attain a close-packed state (to increasedensity), and H converted to atoms by the plasma is bound to unboundseeds to inactivate the amorphous phase, increasing moisture absorptionresistance.

[0103] That is, according to the present embodiment, the mixed gasnozzle 17 serves as promoting gas introduction means, the line for newlyincorporating the H₂ gas 13 a and the mixed gas nozzle 17 serve asinactivating gas introduction means, and the H₂ gas 13 a serves as anamorphous phase inactivating gas. A nozzle for separately introducingthe H₂ gas 13 a may be provided to constitute the inactivating gasintroduction means.

[0104] The most superficial surface of the BNC film 18 is normally in arough state. Thus, if other metal (for example, copper: Cu) is wired inthis condition, diffusion of Cu occurs. According to the presentembodiment, the flow rate of B₂H₆ is made an excess value at the finalstage of film formation, thereby promoting the occurrence of anamorphous phase and increasing density. In addition, an amorphous phaseis known to be the origin of moisture absorption, as stated earlier.Thus, the H₂ gas 13 a is incorporated to bind H to unbound seeds,thereby inactivating the amorphous phase, namely, increasing moistureabsorption resistance. Hence, diffusion of Cu is suppressed withoutimpairment of moisture absorption resistance.

[0105] As described above, the BNC film 18 is produced which has theinterface where the occurrence of an amorphous phase has beensuppressed, and the most superficial surface where the occurrence of anamorphous phase has been promoted to increase density, and where theamorphous phase has been inactivated. By so doing, moisture absorptionresistance at the interface with the substrate can be improved.Furthermore, diffusion of Cu can be suppressed without impairment ofmoisture absorption properties.

[0106] The fourth embodiment will be described based on FIG. 8. FIG. 8is a schematic side view of a plasma CVD apparatus as a film formingapparatus for performing the film forming method according to the fourthembodiment of the present invention. The same constituent members as themembers shown in FIGS. 1 to 4 are assigned the same numerals, andduplicate explanations are omitted.

[0107] The container 1 is provided with a nitrogen gas nozzle 12, asnitrogen gas introduction means, for introducing a nitrogen gas (N₂ gas)11 (>99.999%) into the film formation chamber 2. A diborane gas nozzle14, as boron-based gas introduction means, is provided for introducing adiborane(B₂H₆)-containing gas 13, as a boron-based gas, to the interiorof the film formation chamber 2 below the nitrogen gas nozzle 12. TheB₂H₆-containing gas 13 introduced into the film formation chamber 2through the diborane gas nozzle 14 is a B₂H₆ gas (1% to 5%) diluted witha hydrogen (H₂) gas. A winding-shaped carbon heater 14 a is installedwithin the diborane gas nozzle 14, and the winding-shaped carbon heater14 a is temperature-controlled within the range of 1,000° C. to 3,000°C. by electric current control, whereby the amount of carbon evaporatedis adjusted.

[0108] A hydrocarbon-based gas nozzle 42, as suppressing gasintroduction means, is provided for introducing a hydrocarbon-based gas(for example, methane: CH₄) 41, as an amorphous phase occurrencesuppressing gas, into the interior of the film formation chamber 2 belowthe diborane gas nozzle 14. The CH₄ 41 is introduced through thehydrocarbon-based gas nozzle 42 at the initial stage of film formation.As the amorphous phase occurrence suppressing gas, it is possible toapply the N₂ gas 11 shown in the first embodiment, or the H₂ gas 13 bshown in the second embodiment.

[0109] With the above-described plasma CVD apparatus, a substrate 6 isplaced on an electrostatic chuck 4 and electrostatically attractedthereto. The N₂ gas 11 is introduced at a predetermined flow ratethrough the nitrogen gas nozzle 12, while the B₂H₆-containing gas 13 isintroduced at a predetermined flow rate through the diborane gas nozzle14 equipped with the winding-shaped carbon heater 14 a. Solid-phasecarbon is evaporated by heating of the winding-shaped carbon heater 14a. An electric power is supplied from the high frequency power source 9to the high frequency antenna 7 to apply high frequency waves (1 MHz to100 MHz, 1 kW to 10 kW) via the matching instrument 8. As a result,mainly the N₂ gas 11 is excited within the film formation chamber 2 tochange into a plasma state. After the N₂ gas 11 is excited, it is mixedwith the B₂H₆-containing gas 13 and the evaporated gas from thesolid-phase carbon source, and reacted thereby, whereby a boroncarbonitride (BNC) film 44 is formed on the substrate 6, with thetemperature being controlled by the winding-shaped carbon heater 14 a orthe amount of evaporated carbon being controlled. At this time, thetemperature of the substrate 6 is set at 200° C. to 400° C.

[0110] At the initial stage of film formation, the CH₄ 41 is introducedthrough the hydrocarbon-based gas nozzle 42 to suppress agglomeration ofboron (B), thereby promoting crystallization of BNC and eliminatingcrystal imperfection. Through these means, the occurrence of anamorphous phase at the interface between the substrate 6 and the BNCfilm 44 is suppressed. That is, the CH₄ 41 is introduced at the initialstage of film formation, whereby CH₄ is converted into CH₃+atomic H inthe plasma. The atomic H etches agglomerated B and vaporizes it as BH.Carbon binds to BN, promoting crystallization of BNC.

[0111] Since an amorphous phase is known to be the origin of moistureabsorption, suppression of the occurrence of the amorphous phase at theinterface is very effective for decreasing moisture absorption. Afterinitial-stage film formation, film formation is continued, with the flowrate ratio being returned to the usual ratio. By so doing, there isobtained the BNC film 44 of the desired thickness and maintaining lowdielectric constant properties. The initial-stage film formation ispreferably for a period until a thickness, for example, of the order of100 Å is obtained.

[0112] At the final stage of film formation, the flow rate of B₂H₆through the diborane gas nozzle 14 is rendered present in excess, andthe H₂ gas 13 a is newly mixed into the diborane gas nozzle 14, toenhance imperfection due to B in BNC, thereby promoting the occurrenceof an amorphous phase at the most superficial surface of the BNC film44, and also inactivating the amorphous phase. That is, the occurrenceof the amorphous phase is promoted to attain a close-packed state (toincrease density), and H converted to atoms by the plasma is bound tounbound seeds to inactivate the amorphous phase, thereby increasingmoisture absorption resistance.

[0113] As the boron-based gas, boron chloride (BCl₃) can be appliedinstead of the B₂H₆-containing gas. In this case, the flow rate of BCl₃is rendered present in excess at the final stage of film formation,whereby imperfection due to B in BNC is enhanced to attain aclose-packed state (to increase density).

[0114] That is, according to the present embodiment, the diborane gasnozzle 14 serves as promoting gas introduction means, the line for newlyincorporating the H₂ gas 13 a and the diborane gas nozzle 14 serve asinactivating gas introduction means, and the H₂ gas 13 a serves as anamorphous phase inactivating gas. A nozzle for separately introducingthe H₂ gas 13 a may be provided to constitute the inactivating gasintroduction means.

[0115] The most superficial surface of the BNC film 44 is normally in arough state. Thus, if other metal (for example, copper: Cu) is wired inthis condition, diffusion of Cu occurs. According to the presentembodiment, the flow rate of B₂H₆ is made an excess value at the finalstage of film formation, thereby promoting the occurrence of anamorphous phase and increasing density. In addition, an amorphous phaseis known to be the origin of moisture absorption, as stated earlier.Thus, the H₂ gas 13 a is incorporated to bind H to unbound seeds,thereby inactivating the amorphous phase, namely, increasing moistureabsorption resistance. Hence, diffusion of Cu is suppressed withoutimpairment of moisture absorption resistance.

[0116] As described above, the BNC film 44 is produced which has theinterface where the occurrence of an amorphous phase has beensuppressed, and the most superficial surface where the occurrence of anamorphous phase has been promoted to increase density, and where theamorphous phase has been inactivated. By so doing, moisture absorptionresistance at the interface with the substrate can be improved.Furthermore, diffusion of Cu can be suppressed without impairment ofmoisture absorption properties.

[0117] In the foregoing first to fourth embodiments, the use of the newH₂ gas 13 a as the amorphous phase inactivating gas has been taken as anexample for illustration. However, with the plasma being stopped, ahydrocarbon material, e.g., methane (CH₄), as the amorphous phaseinactivating gas can be heated, for example, by a tungsten heater andintroduced (introduced under vacuum conditions). At this time, CH₄ isconverted into CH₃+H upon heating, and H binds to unbound seeds toinactivate the amorphous phase in the same manner as stated above. Asthe amorphous phase inactivating gas, moreover, a mixture of ahydrocarbon material such as methane (CH₄) and a hydride such as an H₂gas can be heated, for example, by a tungsten heater and introduced(introduced under vacuum conditions).

[0118] The above-described first to fourth embodiments have also shownexamples in which the treatment at the initial stage of film formationand the treatment at the final stage of film formation were bothperformed. However, only one of the treatments can be performed. Acombination of the techniques for treatments may be a suitablecombination of the techniques shown in the first to fourth embodiments.

INDUSTRIAL APPLICABILITY

[0119] As described above, the invention provides the film formingmethod and the film forming apparatus which can form a boron nitridefilm improved in moisture absorption resistance at the interface with asubstrate and maintaining low dielectric constant properties.

1. A film forming method comprising generating a plasma within a filmformation chamber, exciting mainly a nitrogen gas within the filmformation chamber, and then mixing the excited nitrogen gas with aboron-based gas to react them, thereby forming a boron nitride film on asubstrate, characterized by: supplying an amorphous phase occurrencesuppressing gas at an initial stage of film formation to suppressoccurrence of an amorphous phase on an interface.
 2. A film formingmethod comprising generating a plasma within a film formation chamber,exciting mainly a nitrogen gas within the film formation chamber, andthen mixing the excited nitrogen gas with a boron-based gas to reactthem, thereby forming a boron nitride film on a substrate, characterizedby: rendering a flow rate of the nitrogen gas present in excess at aninitial stage of film formation to suppress occurrence of an amorphousphase on an interface.
 3. A film forming method comprising generating aplasma within a film formation chamber, exciting mainly a nitrogen gaswithin the film formation chamber, and then mixing the excited nitrogengas with a boron-based gas to react them, thereby forming a boronnitride film on a substrate, characterized by: rendering a flow rate ofa hydrogen gas present in excess at an initial stage of film formationto suppress occurrence of an amorphous phase on an interface.
 4. A filmforming method comprising generating a plasma within a film formationchamber, exciting mainly a nitrogen gas within the film formationchamber, and then mixing the excited nitrogen gas with a boron-based gasand an organic gas or evaporated carbon to react them, thereby forming aboron carbonitride film on a substrate, characterized by: supplying anamorphous phase occurrence suppressing gas at an initial stage of filmformation to suppress occurrence of an amorphous phase on an interface.5. A film forming method comprising generating a plasma within a filmformation chamber, exciting mainly a nitrogen gas within the filmformation chamber, and then mixing the excited nitrogen gas with aboron-based gas and an organic gas or evaporated carbon to react them,thereby forming a boron carbonitride film on a substrate, characterizedby: rendering a flow rate of the nitrogen gas present in excess at aninitial stage of film formation to suppress occurrence of an amorphousphase on an interface.
 6. A film forming method comprising generating aplasma within a film formation chamber, exciting mainly a nitrogen gaswithin the film formation chamber, and then mixing the excited nitrogengas with a boron-based gas and an organic gas or evaporated carbon toreact them, thereby forming a boron carbonitride film on a substrate,characterized by: rendering a flow rate of a hydrogen gas present inexcess at an initial stage of film formation to suppress occurrence ofan amorphous phase on an interface.
 7. A film forming method comprisinggenerating a plasma within a film formation chamber, exciting mainly anitrogen gas within the film formation chamber, and then mixing theexcited nitrogen gas with a boron-based gas and an organic gas orevaporated carbon to react them, thereby forming a boron carbonitridefilm on a substrate, characterized by rendering a flow rate of ahydrocarbon-based gas present in excess at an initial stage of filmformation to suppress occurrence of an amorphous phase on an interface.8. A film forming method comprising generating a plasma within a filmformation chamber, exciting mainly a nitrogen gas within the filmformation chamber, and then mixing the excited nitrogen gas with aboron-based gas to react them, thereby forming a boron nitride film on asubstrate, characterized by: rendering a flow rate of the boron-basedgas present in excess at a final stage of film formation to promoteoccurrence of an amorphous phase on a surface of the film, and alsomixing an amorphous phase inactivating gas.
 9. A film forming methodcomprising generating a plasma within a film formation chamber, excitingmainly a nitrogen gas within the film formation chamber, and then mixingthe excited nitrogen gas with a boron-based gas to react them, therebyforming a boron nitride film on a substrate, characterized by: renderinga flow rate of the boron-based gas present in excess at a final stage offilm formation to promote occurrence of an amorphous phase on a surfaceof the film, and also mixing a hydride to inactivate the amorphousphase.
 10. A film forming method comprising generating a plasma within afilm formation chamber, exciting mainly a nitrogen gas within the filmformation chamber, and then mixing the excited nitrogen gas with aboron-based gas and an organic gas or evaporated carbon to react them,thereby forming a boron carbonitride film on a substrate, characterizedby: rendering a flow rate of the boron-based gas present in excess at afinal stage of film formation to promote occurrence of an amorphousphase on a surface of the film, and also mixing an amorphous phaseinactivating gas.
 11. A film forming method comprising generating aplasma within a film formation chamber, exciting mainly a nitrogen gaswithin the film formation chamber, and then mixing the excited nitrogengas with a boron-based gas and an organic gas or evaporated carbon toreact them, thereby forming a boron carbonitride film on a substrate,characterized by: rendering a flow rate of the boron-based gas presentin excess at a final stage of film formation to promote occurrence of anamorphous phase on a surface of the film, and also mixing a hydride toinactivate the amorphous phase.
 12. A film forming method comprisinggenerating a plasma within a film formation chamber, exciting mainly anitrogen gas within the film formation chamber, and then mixing theexcited nitrogen gas with a boron-based gas and an organic gas orevaporated carbon to react them, thereby forming a boron carbonitridefilm on a substrate, characterized by: rendering a flow rate of theboron-based gas present in excess at a final stage of film formation topromote occurrence of an amorphous phase on a surface of the film, andalso stopping the plasma and mixing a hydrocarbon material to inactivatethe amorphous phase.
 13. A film forming method comprising generating aplasma within a film formation chamber, exciting mainly a nitrogen gaswithin the film formation chamber, and then mixing the excited nitrogengas with a boron-based gas and an organic gas or evaporated carbon toreact them, thereby forming a boron carbonitride film on a substrate,characterized by: rendering a flow rate of the boron-based gas presentin excess at a final stage of film formation to promote occurrence of anamorphous phase on a surface of the film, and also stopping the plasmaand mixing a hydride and a hydrocarbon material to inactivate theamorphous phase.
 14. A film forming method comprising generating aplasma within a film formation chamber, exciting mainly a nitrogen gaswithin the film formation chamber, and then mixing the excited nitrogengas with a boron-based gas to react them, thereby forming a boronnitride film on a substrate, characterized by: supplying an amorphousphase occurrence suppressing gas at an initial stage of film formationto suppress occurrence of an amorphous phase on an interface, renderinga flow rate of the boron-based gas present in excess at a final stage offilm formation to promote occurrence of an amorphous phase on a surfaceof the film, and also mixing an amorphous phase inactivating gas.
 15. Afilm forming method comprising generating a plasma within a filmformation chamber, exciting mainly a nitrogen gas within the filmformation chamber, and then mixing the excited nitrogen gas with aboron-based gas and an organic gas or evaporated carbon to react them,thereby forming a boron carbonitride film on a substrate, characterizedby: supplying an amorphous phase occurrence suppressing gas at aninitial stage of film formation to suppress occurrence of an amorphousphase on an interface, rendering a flow rate of the boron-based gaspresent in excess at a final stage of film formation to promoteoccurrence of an amorphous phase on a surface of the film, and alsomixing an amorphous phase inactivating gas.
 16. The film forming methodof any one of claims 1 to 15, characterized in that the boron-based gasis a diborane gas diluted with a hydrogen gas.
 17. A film formingapparatus comprising: plasma generation means provided in an upper partof a film formation chamber for generating a plasma within the filmformation chamber; a substrate holding portion provided in a lower partof the film formation chamber; nitrogen gas introduction means forintroducing a nitrogen gas into the film formation chamber; boron-basedgas introduction means for introducing a boron-based gas to an interiorof the film formation chamber below the nitrogen gas introduction means;and suppressing gas introduction means for introducing an amorphousphase occurrence suppressing gas at an initial stage of film formationin order to suppress occurrence of an amorphous phase on an interface.18. A film forming apparatus comprising: plasma generation meansprovided in an upper part of a film formation chamber for generating aplasma within the film formation chamber; a substrate holding portionprovided in a lower part of the film formation chamber; nitrogen gasintroduction means for introducing a nitrogen gas into the filmformation chamber; boron-based gas introduction means for introducing aboron-based gas to an interior of the film formation chamber below thenitrogen gas introduction means; and suppressing gas introduction meansfor introducing a nitrogen gas at an initial stage of film formation inorder to render a flow rate of the nitrogen gas present in excess withinthe film formation chamber and suppress occurrence of an amorphous phaseon an interface.
 19. A film forming apparatus comprising: plasmageneration means provided in an upper part of a film formation chamberfor generating a plasma within the film formation chamber; a substrateholding portion provided in a lower part of the film formation chamber;nitrogen gas introduction means for introducing a nitrogen gas into thefilm formation chamber; boron-based gas introduction means forintroducing a boron-based gas to an interior of the film formationchamber below the nitrogen gas introduction means; and suppressing gasintroduction means for introducing a hydrogen gas at an initial stage offilm formation in order to render a flow rate of the nitrogen gaspresent in excess within the film formation chamber and suppressoccurrence of an amorphous phase on an interface.
 20. A film formingapparatus comprising: plasma generation means provided in an upper partof a film formation chamber for generating a plasma within the filmformation chamber; a substrate holding portion provided in a lower partof the film formation chamber; nitrogen gas introduction means forintroducing a nitrogen gas into the film formation chamber; boron-basedgas introduction means for introducing a boron-based gas and an organicgas or evaporated carbon to an interior of the film formation chamberbelow the nitrogen gas introduction means; and suppressing gasintroduction means for introducing an amorphous phase occurrencesuppressing gas at an initial stage of film formation in order tosuppress occurrence of an amorphous phase on an interface.
 21. A filmforming apparatus comprising: plasma generation means provided in anupper part of a film formation chamber for generating a plasma withinthe film formation chamber; a substrate holding portion provided in alower part of the film formation chamber; nitrogen gas introductionmeans for introducing a nitrogen gas into the film formation chamber;boron-based gas introduction for introducing a boron-based gas and anorganic gas or evaporated carbon to an interior of the film formationchamber below the nitrogen gas introduction means; and suppressing gasintroduction means for introducing a nitrogen gas at an initial stage offilm formation in order to render a flow rate of the nitrogen gaspresent in excess within the film formation chamber and suppressoccurrence of an amorphous phase on an interface.
 22. A film formingapparatus comprising: plasma generation means provided in an upper partof a film formation chamber for generating a plasma within the filmformation chamber; a substrate holding portion provided in a lower partof the film formation chamber; nitrogen gas introduction means forintroducing a nitrogen gas into the film formation chamber; boron-basedgas introduction means for introducing a boron-based gas and an organicgas or evaporated carbon to an interior of the film formation chamberbelow the nitrogen gas introduction means; and suppressing gasintroduction means for introducing a hydrogen gas at an initial stage offilm formation in order to render a flow rate of the hydrogen gaspresent in excess within the film formation chamber and suppressoccurrence of an amorphous phase on an interface.
 23. A film formingapparatus comprising: plasma generation means provided in an upper partof a film formation chamber for generating a plasma within the filmformation chamber; a substrate holding portion provided in a lower partof the film formation chamber; nitrogen gas introduction means forintroducing a nitrogen gas into the film formation chamber; boron-basedgas introduction means for introducing a boron-based gas and an organicgas or evaporated carbon to an interior of the film formation chamberbelow the nitrogen gas introduction means; and suppressing gasintroduction means for introducing a hydrocarbon-based gas at an initialstage of film formation in order to render a flow rate of thehydrocarbon-based gas present in excess within the film formationchamber and suppress occurrence of an amorphous phase on an interface.24. A film forming apparatus comprising: plasma generation meansprovided in an upper part of a film formation chamber for generating aplasma within the film formation chamber; a substrate holding portionprovided in a lower part of the film formation chamber; nitrogen gasintroduction means for introducing a nitrogen gas into the filmformation chamber; boron-based gas introduction means for introducing aboron-based gas to an interior of the film formation chamber below thenitrogen gas introduction means; promoting gas introduction means forrendering a flow rate of the boron-based gas present in excess at afinal stage of film formation to promote occurrence of an amorphousphase on a surface of a film; and inactivating gas introduction meansfor mixing an amorphous phase inactivating gas at the final stage offilm formation.
 25. A film forming apparatus comprising: plasmageneration means provided in an upper part of a film formation chamberfor generating a plasma within the film formation chamber; a substrateholding portion provided in a lower part of the film formation chamber;nitrogen gas introduction means for introducing a nitrogen gas into thefilm formation chamber; boron-based gas introduction means forintroducing a boron-based gas to an interior of the film formationchamber below the nitrogen gas introduction means; promoting gasintroduction means for rendering a flow rate of the boron-based gaspresent in excess at a final stage of film formation to promoteoccurrence of an amorphous phase on a surface of a film; andinactivating gas introduction means for mixing a hydrogen gas at thefinal stage of film formation in order to inactivate the amorphousphase.
 26. A film forming apparatus comprising: plasma generation meansprovided in an upper part of a film formation chamber for generating aplasma within the film formation chamber; a substrate holding portionprovided in a lower part of the film formation chamber; nitrogen gasintroduction means for introducing a nitrogen gas into the filmformation chamber; boron-based gas introduction means for introducing aboron-based gas and an organic gas or evaporated carbon to an interiorof the film formation chamber below the nitrogen gas introduction means;promoting gas introduction means for rendering a flow rate of theboron-based gas present in excess at a final stage of film formation topromote occurrence of an amorphous phase on a surface of a film; andinactivating gas introduction means for mixing an amorphous phaseinactivating gas at the final stage of film formation.
 27. A filmforming apparatus comprising: plasma generation means provided in anupper part of a film formation chamber for generating a plasma withinthe film formation chamber; a substrate holding portion provided in alower part of the film formation chamber; nitrogen gas introductionmeans for introducing a nitrogen gas into the film formation chamber;boron-based gas introduction means for introducing a boron-based gas andan organic gas or evaporated carbon to an interior of the film formationchamber below the nitrogen gas introduction means; promoting gasintroduction means for rendering a flow rate of the boron-based gaspresent in excess at a final stage of film formation to promoteoccurrence of an amorphous phase on a surface of a film; andinactivating gas introduction means for mixing a nitride at the finalstage of film formation in order to inactivate the amorphous phase. 28.A film forming apparatus comprising: plasma generation means provided inan upper part of a film formation chamber for generating a plasma withinthe film formation chamber; a substrate holding portion provided in alower part of the film formation chamber; nitrogen gas introductionmeans for introducing a nitrogen gas into the film formation chamber;boron-based gas introduction means for introducing a boron-based gas andan organic gas or evaporated carbon to an interior of the film formationchamber below the nitrogen gas introduction means; promoting gasintroduction means for rendering a flow rate of the boron-based gaspresent in excess at a final stage of film formation to promoteoccurrence of an amorphous phase on a surface of a film; andinactivating gas introduction means for mixing a hydrocarbon material atthe final stage of film formation in order to inactivate the amorphousphase.
 29. A film forming apparatus comprising: plasma generation meansprovided in an upper part of a film formation chamber for generating aplasma within the film formation chamber; a substrate holding portionprovided in a lower part of the film formation chamber; nitrogen gasintroduction means for introducing a nitrogen gas into the filmformation chamber; boron-based gas introduction means for introducing aboron-based gas and an organic gas or evaporated carbon to an interiorof the film formation chamber below the nitrogen gas introduction means;promoting gas introduction means for rendering a flow rate of theboron-based gas present in excess at a final stage of film formation topromote occurrence of an amorphous phase on a surface of a film; andinactivating gas introduction means for mixing a hydride and ahydrocarbon material at the final stage of film formation in order toinactivate the amorphous phase.
 30. A film forming apparatus comprising:plasma generation means provided in an upper part of a film formationchamber for generating a plasma within the film formation chamber; asubstrate holding portion provided in a lower part of the film formationchamber; nitrogen gas introduction means for introducing a nitrogen gasinto the film formation chamber; boron-based gas introduction means forintroducing a boron-based gas to an interior of the film formationchamber below the nitrogen gas introduction means; suppressing gasintroduction means for introducing an amorphous phase occurrencesuppressing gas at an initial stage of film formation in order tosuppress occurrence of an amorphous phase on an interface; promoting gasintroduction means for rendering a flow rate of the boron-based gaspresent in excess at a final stage of film formation to promoteoccurrence of an amorphous phase on a surface of a film; andinactivating gas introduction means for mixing an amorphous phaseinactivating gas at the final stage of film formation.
 31. A filmforming apparatus comprising: plasma generation means provided in anupper part of a film formation chamber for generating a plasma withinthe film formation chamber; a substrate holding portion provided in alower part of the film formation chamber; nitrogen gas introductionmeans for introducing a nitrogen gas into the film formation chamber;boron-based gas introduction means for introducing a boron-based gas andan organic gas or evaporated carbon to an interior of the film formationchamber below the nitrogen gas introduction means; suppressing gasintroduction means for introducing an amorphous phase occurrencesuppressing gas at an initial stage of film formation in order tosuppress occurrence of an amorphous phase on an interface; promoting gasintroduction means for rendering a flow rate of the boron-based gaspresent in excess at a final stage of film formation to promoteoccurrence of an amorphous phase on a surface of a film; andinactivating gas introduction means for mixing an amorphous phaseinactivating gas at the final stage of film formation.